This was a temporary block while a vandalism issue is resolved. See discussion at https://community.openstreetmap.org/t/how-about-limit-new-accounts/101656/253 .

Please contact OSM’s Data Working Group by email at data@openstreetmap.org for full details of what we think happened.

As a general note - to avoid this sort of thing, people should ensure that they don’t share passwords between accounts for different things on the internet (so that if passwords for site A get published, they aren’t useful for site B).